This invention generally relates to electrical connectors for miniature or microminiature contact systems. Despite their miniaturization, these connectors are manufactured in a traditional manner, while addressing a concern of solder flux wetting. A barrier member is included in each contact assembly in order to thereby prevent passage of liquids such as solder flux from one face of the connector to the opposite face of the connector.
Electronic packages having miniature and microminiature electronic components are characterized by being especially small, dense and more efficient, leading to many challenges, including those associated with physically and electrically connecting package components together. Examples of packages include chips which are characterized by having a high circuit count in a small area. Often, these dense conditions include providing an array of terminals or contacts which are closely spaced from one another and which must remain electrically insulated from one another so as to provide a plurality of discrete electrical connections, typically in an ordered, predetermined array. An example of a connector of this type is one having a land grid array of contact pads.
An approach which has been developed for manufacturing such miniature and microminiature contact systems involves electroforming using a gold wire bonding preform. In this approach, the printed circuit board component is manufactured, as is the gold wire bonding preform. The preform is attached to the board, followed by plating and electroforming the contact, requiring approximately a two hour plating process in order to plate the contact finish. This process next etches and individualizes the contact. Overall, this process includes mask placement, followed by paste placement and solder ball placement, with attendant reflow. Thereafter, removal from the panel is carried out. This technology is exemplified by U.S. Pat. No. 5,476,211 and No. 5,864,946, incorporated by reference hereinto. A characteristic of this technology is that the same is suitable for low normal force systems of about 1 gram per mil. Another characteristic of this approach is that the contacts have limited compliance, the total range being 0.015 inch, and the working range being 0.008 inch. The electrical characteristics are as follows: self-inductance of 1.78 nh, loop inductance of 2.0 nh, and impedance of 90 ohms. Systems of this type are also characterized as being expensive.
While the approach summarized in the preceding paragraph is useful in addressing miniaturization and microminiaturization of contact systems, its attendant disadvantages, especially its limited compliance and cost, reduce its desirability. Traditional contact system manufacturing approaches can be problematic when miniaturization to this degree is to be practiced. In addition to the complications which arise in manufacture and assembly of such small components, they also can be susceptible to undesired flow of liquids therethrough. For example, soldering flux can flow from a face of the grid being subjected to soldering to an opposite face of the grid which is to provide unsoldered contact functions. This latter concern is especially of interest in those applications where the connector does not experience contact wiping.
Accordingly, there is a need for miniaturized connectors which can be manufactured efficiently without proceeding with an electroforming operation, while also addressing compliance and flux wetting issues.